PCT patent application Ser. No. 97/21090 describes a microanalytical/microsynthetic system for biological and chemical analysis which comprises a rotatable microplatform, for example a disk, having inlet ports, microchannels, detection chambers and outlet ports through which may flow.
It has now been found that microfluidic devices can be prepared in which fluid flow may be controlled by having different surfaces of the substrate forming the device having different surface characteristics. By “microfluidic devices” is meant devices that can handle microvolumes of reagents, for example samples of less than 1 μl, suitably less than 500 nl and preferably between 1 and 10 nl, may be introduced into the device. By “fluid” is meant dry powders and liquids, including suspensions of particulates in liquids.